Furnace cooling system

ABSTRACT

A shaft furnace, such as a blast furnace, has hollow cooling staves extending transversely around the circumference of the furnace in the shaft wall lining. The upper portions of the staves are substantially wider than the lower portions, and preferably extend inwardly into the furnace lining, to provide support for the furnace lining above the staves. Preferably the staves are arranged so that certain of them are located above other staves, the upper portions of the lower staves being substantially wider than the lower portions of the staves above them, to aid in supporting the lining. Where the furnace has a mantle at the lower end of the shaft portion extending inwardly of the furnace shell and forming a reentrant corner, the staves are preferably disposed in the lining in the reentrant corner in the vicinity of the mantle, with the wider upper portions of the staves projecting into the lining to support the lining, and to distribute the load of the lining downwardly into the reentrant corner.

United States Patent [72) lnventors Melvin J. Greaves Cleveland;

Tage Werner. Rocky River, both of, Ohio [2]] Appl. No. 883,220 [22]Filed Dec. 8, 1969 Division of Ser. No. 778.883. Aug. 29. I968. which isa Division of Ser. No. 520.945.,lan. 16. I966. Pat. No. 3.431.69l.

[45} Patented June 22, 1971 [73] Assignee Arthur G. McKee 8: CompanyCleveland, Ohio [54] FURNACE COOLING SYSTEM lll FOREIGN PATENTSI,O39,082 9/1958 Germany ABSTRACT: A shaft furnace, such as a blastfurnace, has hollow cooling staves extending transversely around thecircum ference of the furnace in the shaft wall lining. The upperportions of the staves are substantially wider than the lower portions,and preferably extend inwardly into the furnace lining, to providesupport for the furnace lining above the staves. Preferably the stavesare arranged so that certain of them are located above other staves, theupper portions of the lower staves being substantially wider than thelower portions of the staves above them, to aid in supporting thelining. Where the furnace has a mantle at the lower end of the shaftportion extending inwardly of the furnace shell and forming a reentrantcomer, the staves are preferably disposed in the lining in the reentrantcorner in the vicinity of the mantle, with the wider upper portions ofthe staves projecting into the lining to support the lining, and todistribute the load of the lining downwardly into the reentrant comer.

FURNACE COOLING SYSTEM CROSS-REFERENCE TO RELATED APPLICATIONS Thisapplication is a division of applicants copending U.S. application Ser.No. 778,883 filed Aug. 29, 1968, which is a division of US. applicationSer. No. 520,945 filed Jan. 16, 1966 now U.S. Pat. No. 3,43l,691 datedMar. [1,1969.

DISCLOSURE This invention relates to shaft furnace structures such asblast furnaces, and more particularly to improved means for cooling suchshaft furnaces.

In the United States, blast furnace structures heretofore conventionallyused generally have includeda massive foundation set into the earth; thelower portion of the furnace including the hearth and bosh has beensupported by this foundation. The upper portion of the furnace,including the shaft and furnace top including the bells, distributor andupper portions of the downcomer, has been supported by a m'antle that,in turn, has been supported on the foundation by numerous columnssurrounding the lower portion of the furnace in close proximity to eachother and to the lower portion of the furnace.

Such furnace structures have certain advantages in that the upper partof the furnace including the shaft and top supported by the mantle havebeen free to expand thermally as a unit on heating of the furnace. Thedowncomer attached to the furnace top also becomes heated duringoperation of'the furnace, so it also expands and contracts with theportion of the furnace above the mantle, thus minimizing difficultiesthat might otherwise arise from thermal expansion.

However, in such furnace structures there have been substantialdifficulties arising from the differences in the thermal expansions ofthe supporting columns and the lower portion of the furnace below themantle. The mantle-supporting columns themselves are not subjected tosufficient heat to cause them to expand appreciably, but the lowerportion of the furnace is subjected to high temperature heat; therefore,the lower ortion of the furnace tends to expand substantially on heatingof the furnace until it bears substantially all of the weight of thefurnace above the mantle and the apparatus supported by such portion ofthe furnace. On cooling, the lower portion of the furnace contracts andthe entire load again is transferred to the columns. lt, therefore hasnecessarily been the practice to make the columns strong enough tosupport the upper portion of the furnace and apparatus supportedthereby, and also to make the lower portion of the furnace strong enoughto support the upper furnace portion and such apparatus; this hasinvolved substantial added costs. Furthermore, the lining of the furnacein the vicinity of the mantle has been susceptible to excessivedeterioration because of localized expansion and contraction arisingfrom transfer of the load from the columns to the lower portion of thefurnace and vice versa. The expansion joint often provided at thislocation to minimize this problem, itself has been a source of trouble.

In conventional European blast furnace structures, the lower portion ofthe furnace including the hearth and bosh, and the upper portion of thefurnace including the shaft but not the furnace top, are supported froma massive foundation set into the earth. The furnace top, including theloading equipment and downcomers, is supported from this foundation bylong posts or columns. This design tends to overcome the above describeddisadvantage of American-type structures, but introduces new problems.The bosh jacket is a structural element that supports the shaft of thefurnace; consequently, a hot spot in the bosh can impair the support forthe shaft; furthermore, the necessity for maintaining the bosh jacket asa structural supporting member increases the difficulties of reliningthe bosh. This design also makes it difficult to maintain a satisfactorytight joint between the furnace top and the portion of the furnace belowthe top, since the portion of the furnace below the top tends to expandon heating whereas the columns supporting the top don ot expandappreciably if at all; this problem is accentuated when high toppressures are used according to modern practice. Other problems arisebecause the downcomer, supported from the columns, expands due to heatwhile the columns themselves do not expand, and because a portion of thecharge-distributing apparatus is usually supported by the furnace topand moves as the furnace expands, and a portion is supported from theposts and does not move from thermal expansion, so jamming ofdistributor parts or gas leakage at the distributo may occur. 7

In conventional American furnace structures, as well as in most Europeanstructures, the columns or posts that support the upper portions of thefurnaces are so closely spaced in relation to the lower portions of thefurnaces, as well as to each other, that they impair access to the lowerportions of the furnaces for operations such as tapping, closing the tapholes and removing slag or spilled metal; they particularly impairaccess to these portions of the furnaces by automatic machinery forperforming these functions. Moreover, since the legs are closelydisposed relatively to the furnace, they can be damaged by molten metalin the event of breakouts. Furthermore, in both American and Europeanfurnace structures, it is very difficult, time-consuming and expensiveto line the furnace, particularly the bosh and lower inwall portionswhich most frequently require lining, primarily because of thedifficulties of access to the furnace caused by the closely spacedcolumns and by the constructions of the bosh and hearth portions whichmust act as supports for the upper furnace portions.

It is an object of the present invention to overcome as many of theseproblems and disadvantages as are desired. Another object is theprovision of a blast furnace structure in which the portion of thefurnace above the bosh, including the top, may be largely, or if desiredentirely, supported by legs or columns at all times during heating andcooling of the furnace. This minimizes or eliminates disadvantages ofAmerican-type furnace structures such as those arising out of transferof the support of the portion of the furnace above the mantle from thesupporting columns to the lower portion of the furnace and vice versaand also eliminates the disadvantages of Europeantype furnace structuressuch as those arising from the necessity to maintain the bosh jacket asa support for the shaft, from the difficulty of sealing theindependently supported furnace top to the shaft, and from expansion ofthe downcomers and distributor parts relative to the nonexpandingsupporting posts supporting the furnace top.

A further object is the provision of a blast furnace structure in whichthe portions of the furnace above the mantle location, as well as thefurnace top if desired, are supported by widely spaced legs that permitgreatly increased access to the furnace for operations and use ofautomated equipment and repair or replacement of lining, and that reducepossibilities of damage to the legs in the event of breakouts of moltenmetal. Another object is the provision of a furnace structure of theabove type in which the hearth is suspended from the furnace shell andnot supported from below, so that the entire furnace is supported at alltimes from legs and both the upper portion and the lower portion of thefurnace can freely thermally expand and contract. Another object is theprovision of improved means for cooling the wall of the furnace.

These and other objects of the invention will be apparent from thefollowing description of several embodiments of the invention inconnection with the accompanying drawings in which:

FIG. I is a perspective of a blast furnace structure embodying theinvention and having a suspended hearth portion, parts not pertinent tothe disclosure being omitted for clearness;

FIG. 2 is a vertical cross section, along line 2-2 of FIG. 1, partsbeing omitted for clearness;

FIG. 3 is a section along line 33 of FIG. 2 showing in plan the mainsupporting frame and lower centering means for the furnace, the scalebeing larger than in FIGS. 1 and 2',

FIG. 4 is an enlarged detail along line 4-4 of FIG. 1 showing one of themeans connecting the surrounding frame of the supporting structure tothe furnace shell;

7 FIG. 5 is a cross section along line 5-5 of FIG. 2 and to the samescale showing means for centering the upper portion of the furnace;

FIG. 6 is a somewhat diagrammatic side elevation of the supportingstructure, illustrating prestressing and preforming of the supportingstructure before the load is applied;

FIG. 7 is a vertical section to an enlarged scale of one of the supportsfor the legs;

FIG. 8 is a section along line 8-8 of FIG. 7;

FIG. 9 is a detail of another embodiment of the invention in which thehearth is supported from the bottom but in which the remainder of thefurnace structure is essentially the same as in FIGS. I-8, parts beingomitted for clearness;

FIG. 10 is an enlarged detail, corresponding generally to FIG. 4 in thelocation from which the section is taken, showing alternative means forconnecting the surrounding frame to the furnace of FIG. 9 andalternative cooling means; and

FIG. 11 is an enlarged detail, also corresponding generally to FIG. 4 inthe location of the section, of another embodiment showing another meansfor connecting the furnace to a surrounding supporting frame.

In the furnace structure of FIGS. 1 to 8 inclusive, the furnace 1 issupported entirely free of the ground by supporting structure 2. Thefurnace I comprises shaft 3, bosh 4 and hearth portion 5, all enclosedin a continuous steel shell 6 free of sharp bends below its connectionto supporting structure 2 to prov de adequate strength for the suspendedportion of the furnace. Shell 6 comprises shaft shell portion 7, boshjacket 8 and hearth jacket 9. The furnace top is generally indicated as10.

The supporting structure 2 comprises a frame 12, surrounding and spacedfrom the furnace 1 in the vicinity of the ring 13, which is preferablylocated in essentially the same vertical relationship to furnace shaft 3as a mantle in a conventional furnace. Frame 12 is supported by fourlegs 14 from foundation members 15 set into the earth.

The furnace top 10 of the illustrated structure is conventional andincludes a large bell hopper 16 containing a large bell (not shown), asuperposed rotatable distributor 17, the lower end of which is closed bya small bell (not shown), and a receiving hopper 18 above thedistributor into which burden or charge material is charged. All ofthese parts are supported by the furnace from the top of the furnaceshaft. Burden material may be conventionally charged into the receivinghopper by belts or skip cars traveling on a bridge (not shown).

Uptakes 21 are connected in conventional manner to the interior of thetop portion of the furnace, and discharge into a downcomer 22 connectedin the usual manner with a dust catcher, gas washer, stoves, etc., notshown. These uptakes and the upper portion of the downcomer are alsosupported from the top of the shaft of furnace I.

An auxiliary frame structure.23 is located above and rigidly supportedfrom supporting structure 2; it comprises upstanding legs 24 connectedto the supporting structure 2 and carrying a top working platform 25 anda lower working platform 26, the upper end of the skip or belt conveyorbridge, as well as superstructure 27 that supports the repair crane 28and other parts usually associated with the top of a furnace.

The furnace also includes conventional bustle pipe 29 surrounding thebosh, tuyeres 31, and associated cooling water collecting trough 32. Aworking or cast house floor 33 at the lower end of the furnace carriesthe iron runners 34 extending away from the iron notches 35 and a slagrunner 36 extending away from the slag notch 37 in the furnace hearth.This floor is preferably supported independently of the legs 14 of thefurnace structure.

In the supporting structure 2, the frame 12 of the illustrated apparatusis made up of four deep steel beams 38 that are welded or bolted attheir ends to form a square in plan (FIG. 3). Each of the illustratedbeams, which may be about 10 feet 2 deep, is an l-section girder havinga wide vertical web 39, top

and bottom flanges 40 and 41, and reinforcing stiffeners 42 (FIG. II);it may be conventionally fabricated, as by welding, from steel plates.The four legs 14 are rigidly connected to frame 12 at the four cornersthereof, as by welding or bolting.

At each of eight points of equal deflection on the frame 12, a connectormember 43 connects the adjacent I-beam 38 to the blast furnace shell 6in the vicinity of the juncture of the shaft and bosh portions of thefurnace preferably at a location such that when the furnace isempty orfilled the center of gravity of the furnace is below a horizontal planecontaining the center of gravity of the frame 12.

Each of these connector members 43, as shown in FIGS. 1 to 4, comprisesa flat member, preferably formed of thick steel plate, that extendsinwardly from the web 39 of the associated l-beam 38 of the frame 12 tothe shaft portion 7 of the furnace shell 6 and is rigidly fixed, as bywelding or bolting, to both the l-beam and the furnace shell. Thesemembers 43 are essentially located in spaced vertical planes that extendessentially radially of the furnace shell and pass through and areequiangularly spaced about a vertical axis A that is essentiallycoincident with the vertical axis of the furnace of supporting structure2. The lower portion of each member 43 extends downwardly from thebottom of the I-beam 38 to a structural ring 13 located a substantialdistance below the bottom of I- beam 38 and fixed to the shell 6 of thefurnace at the juncture of shaft shell portion and the bosh jacket 8.Preferably, as shown in FIG. 4, a structural ring 45 is fixed to theshell 6 and the inner edge of each member 43, at a location on the shellbelow the top of frame 12; ring 45 is made ofa radially extending web 46that is welded or bolted to the shell and members 43, and a stiffeningflange 47 that is welded to the web. Rings 13 and 45 are also laterallystiffened by numerous reinforcing gussets 48a and 48b (FIGS. 1 and 4)welded to the shell and the rings. If desired, each connector member 43can be made in two pieces 43a and 43b that are joined along line 50 tofacilitate erection. Upper piece 43a can be fixed to supporting frame12, and lower piece 43b can be attached to the furnace shell 6, afterwhich these parts of each member 43 can be welded together in the field.Members 49 are also fixed, as by welding, to the outer edges ofconnector members 43 and aid in reinforcing them.

A compression ring member 51, shown in the illustrated embodiment asoctagonal with sides of equal length and equal angles between the sides,is fixed, as by welding, to top flanges 40 of the I-beams 38 of the mainframe 12, and has internally extending projecting portions 52 that arewelded or otherwise rigidly fixed to the outer top edges of theconnector members 43. This ring member 51 resists tilting of the beams38 about their longitudinal generally horizontal axes, from the weightof the furnace or from expansion of the furnace shell on heating. As thefurnace heats and its shell increases in diameter, the lower ends of theconnector members 43, which are deep enough so they themselves do notappreciably deflect, tend to move outwardly with the lower portion ofthe shaft shell portion 7 to which is affixed one generally verticaledge of each connector. This causes the upper ends of connectors 43 totend to move inwardly, which tends to cause the beams 38, to which arefixed the other space, generally vertical edges of connectors, to twistabout their longitudinal axes so their upper flanges 40 tend to movecloser to the furnace than their lower flanges 41. However, any tendencyof each I-beam thus to twist or tilt is resisted by the ring member 51that is thus subjected to compressive forces. Reinforcing members 49, oneach side of each connector member 43, also strengthen members 43against buckling. Since the ring member is a symmetrical polygon withstraight sides at the junctures of which the connectors are located, themember is exceptionally efficient in resisting the forces to which it issubjected.

There is a pair of divergent adjustable struts 53 connecting each of thefour sides of the frame 12 to the shell (FIG. 3). These struts areturnbuckle types adjustable as to length. The struts of each pair arepivotally connected to widely spaced lugs 54 on the furnace shell 6essentially equidistant from the midpoint of the adjacent frame beam 38,and to lugs 55 on the web of such beam at locations closely adjacent toand essentially equidistant from its midpoint, preferably nearer the topof the beam than the bottom; these struts are generally tangential toshell 6.

At the upper portion of the furnace pairs of divergent adjustable struts56 similar to struts 53, extend between the top of the furnace shell andthe auxiliary frame structure 23 (FIG. 5). Struts S6 of each pair arepivotally connected to lugs 57 on the furnace shell 6 and to lugs 58 onthe adjacent girder 59 forming the top of the auxiliary frame 23, whichis made strong enough to resist substantial lateral forces. Lugs 57 and58 for each pair of struts are located essentially equidistantly fromthe center of the associated girder 59, below the top platform 25, andeach strut 56 is generally tangential to the furnace shell.

By suitable adjustments of the lengths of struts 53 and 56 it ispossible to cause them to center the furnace in the supporting structureformed of structure 2 and its attached auxiliary frame structure 23, toprevent twisting of the furnace in such structure, and to restrain thefurnace against lateral movement relative to such structure in the eventof seismic or other shocks, all without preventing vertical movements ofthe furnace or portions thereof relative to such structure as mightresult from thermal expansion or contraction. The furnace is thussupported at all times by a strong, stable supporting structure.

In this embodiment, the shaft of the furnace is cooled by generallyhorizontal conventional cooling plates 60, extending transversely aroundthe circumference of the furnace in shaft inwall 61, through whichplates water is circulated by conventional means. The bosh may beconventionally cooled by water applied to its exterior.

The bottom portion 62 (FIGS. 1 and 2) of the hearth jacket 9 portion ofshell 6 preferably is essentially the shape of a hemiellipsoid having acircular cross section, and is lined with a suitable refractory materialsuch as a substantially uniformly thick layer 63 of carbon; the carbonlining in this embodiment continues upwardly at 64 throughout the hearthportion and the bosh up to the shaft inwall 61. The lower portion of thehearth is filled with refractory material, such as carbon or hightemperature refractory brick, to form a massive bottom 65. Thehemiellipsoidal shape of this portion of the hearth jacket is such thatdownwardly acting forces on body 65, resulting from the weights of theliquid metal and the charge material resting on the metal, causesubstantially uniform outwardly directed pressures on the portions 63and 64 of the lining and the portions ofjacket 9 that enclose andsupport the body 65. This hemiellipsoidal shape also minimizesdistortion of the material of body 65 on heating and cooling.

Since the hearth portion of the furnace is suspended completely free ofany bottom support, numerous advantages result. The hearth portion canbe cooled more readily than in conventional furnaces because of thelarge additional cooling area of the exposed bottom. The vertical andhorizontal principal stresses in the hearth and bosh jackets are bothtension stresses, so that shear in the steel jackets and theirrefractory linings is low; this eliminates most if not all the prematurelining failure that occurs at these locations in conventional furnaces,in which the hearth and bosh support upper portions of the furnace, fromthe substantial shear developed in the jackets and lining materialbecause of large horizontal ring stresses. Moreover, the suspendedhearth portion facilitates repairing or replacing the lining of thefurnace, with considerable savings in labor and time, and considerablereduction in furnace downtime, because accessibility is considerablygreater than in conventional furnaces, and it is not necessary todismantle large amounts of auxiliary equipment at the lower portion ofthe furnace as is conventionally necessary. Thus, it is a relativelysimple matter to cut an opening in the wall of the furnace at floor 33and move in men and equipment, including highly automated equipment, forrelining pur- 7 provided if, before loading, the supporting structure 2is prestressed and preformed to cause it be formed and deflected priorto loading so that there is little ifany appreciable deflection visuallyapparent after the furnace structure is completed. Preferably the legs14 and also the beams 38 of the structure 2 are thus prestressed, andeach beam 38 is built with a calculated camber when unloaded, so thateach leg has no moment when subjected to maximum loading, and so thateach beam is essentially flat when subjected to maximum loading.

FIG. 6 shows diagrammatically the shapes of the beams 38 and legs 14 ofa supporting structure 2 embodying the invention when the structure 2 isprestressed but not loaded, and when the structure 2 is loaded with theweight of the furnace and other structure carried by the furnace. Thefull lines show, with great exaggeration of curvature for the sake ofclearness, the shape of the structure 2 from its side when the legs 14,fabricated to have straight axes, are prestressed and curved by havingthe lower ends of their outer legs forced outwardly radially from theaxis A-of the structure 2 and the furnace, to the positions they arecalculated to assume under full load. The beams 38 are also shown infull lines as cambered upwardly when the legs are prestressed. Althoughit might be expected that each beam would be deflected downwardly at itscentral portion because of the forces exerted on the ends of the beam bythe rigid connections of the tops of the legs 14 to the beam ends, inthe illustrated embodiment each beam 38 is fabricated so it has anupward cambered curve essentially identical to the calculated deflectionthat will occur when the beam is loaded with its share of the weight ofthe furnace and other structure supported by beams 38; therefore theprestressing of the legs 14 will deflect the beam sufficiently to removepart, but not all, of the upward camber of beams 38. Beams 38 and legs14 are preferably so designed, and the prestressing of the legs is such,that after the structure is fully loaded there is no visuallyappreciable deflection of the legs and beams so that, as shown by brokenlines of FIG. 6, the legs and the beams are straight and can developtheir maximum strength.

FIGS. 7 and 8 show means for moving the lower ends of the legs radiallyoutwardly to prestress them as described above and to hold the ends insuch position while allowing the lower ends of said legs to rotatefreely, without subjecting the lower ends of the legs to bendingmoments. This means comprises a metal base member 66, fixed as bybolting to each foundation member 15 set into the earth; the uppersurface of this base member is normal to the axis 8 of the leg 14 whenthe leg is straight. An adjustable member 67 rests on member 66; it hasan upwardly open annular groove 68, against the bottom and inner wall 69of which is fixed an annular bearing ring 71 of hardened metal providingan upwardly facing seat 72, spherical about point P. The outer wall '73of the groove 68 extends upwardly to provide a raised guard and guide.

The lower end of each leg 14 is tapered at 74 as shown and terminates ina casting 75 of thick cross section in which is fixed a seat 76 ofhardened metal and shaped to mate with spherical seat 72. Casting 75 hasa flange 77 that extends into the groove 68 adjacent outer wall 73;consequently the lower end of the leg 14 is prevented from movinglaterally off the seat 72 or jumping off the base in the event ofseismic shock or other large disturbances.

To draw the lower end of each leg outwardly to the desired prestressingposition, each member 67 is provided with two diametrically spaced lugs78, each connected by a drawbolt 79 to a lug 81 fixed to the base. Bytightening the nuts 82 on bolts 79 the desired amounts, each member 67supporting the bottom ofa leg 14, can be moved from an initial positionshown in broken lines in FIG. 8 to its prestressing position shown infull lines in such figure without subjecting the leg to bending momentat its lower end, after which locking blocks 83 can be fixed, as bywelding, to the base member 66 to hold the lower end of the leg in thedesired prestressing position to provide the above described desirableresults.

The furnace of FIG. 9 includes a supporting structure 2 like that ofFIGS. l3 including deep I-girders 38 joined at their ends to form aframe 12, that is square in plan configuration, that surrounds and isspaced from furnace 85, and that is supported from its corners by widelyspace legs 14 that, as in the previous embodiment, are prestressedduring erection. This frame 12 is connected to the shell 6 of thefurnace by radially extending equiangularly spaced connector members d3identical with, and fixed to the frame 12 and furnace shell by the samemeans as, connectors 43 of FIGS. 15. A compression ring member 51 andadjustable struts 53 at frame 12, and ad justable struts 56 are alsoprovided to connect the top portion of the furnace to girders 59 ofauxiliary frame structure 23, as in the previous embodiment, to performthe same or similar functions. In the embodiment of FIG. 9, however, thehearth portion 87 of the furnace is supported from beneath by afoundation 88 that is set into the earth. The hearth portion may beconventional in design. The remainder of the furnace structure of FIG. 9may be identical with that of FIGS. 1-5, inclusive, and like parts bearlike reference numerals. No further description is believed necessary.

FIG. 10 shows to a larger scale alternative means for supporting furnace85 of FIG. 9 from supporting structure 2, and alternative cooling means.The furnace shell 89 in this case is conventional and includes a shaftshell portion 91 and a bosh jacket 92 joined at a mantle ring 93. Thesquare frame 12 of the furnace-supporting structure 2 is identical withthat of FIGS. l--4, being made of deep section l-girders 38 that areconnected together at their ends. This frame surrounds the furnace andis supported at the four corners by four legs 14, of which one is shownin FIG. 10. The frame is connected to the furnace shell by connectormembers 94 that, as in the previous embodiment, are equiangularlyradially disposed about the shell in essentially vertical planes. Theseconnectors are connected to the beams 38 forming the frame 1w at pointsof equal deflection of the beams. Each connector member 94 is deep andstiff in a generally vertical direction, preferably formed of steelplate; it is fixed to the web 39 and the insides of the flanges 40 and41 of its associated l-beam 38, and to the furnace shell by being fixedto mantle 93, and to a radially projecting lug or flange 95 fixed toshell 89 by a bolted joining strip 96. Stiffening lugs 97 are preferablyfixed to the mantle for added strength. A ring member 98, preferably ofequalsided, equiangular, octagonal plan shape like ring member 51 ofFIGS. l4, is fixed t the top flanges of the beams 38 forming framemember 12 in the same manner and location as ring member 51. A similarring member 99 is similarly fixed to and located on the bottom flanges41 of the beams 38.

The furnace of FIG. 10 also has generally horizontally extendingconventional cooling plates 101 in the bosh section, through whichplates water is circulated by convention means. The shaft of the furnaceis cooled by hollow cooling staves 102, 103, formed ofiron or othersuitable metal and extending transversely along the circumference of thefurnace in the inwall 104; water is circulated through the staves byconventional means. The upper staves 102 are conventional in that theyare of rectangular cross section; the lower staves 103 differ in thatthe upper portion 105 of each stave is considerably wider than its lowerportion 106; preferably its ex terior top width is about twice itsexterior bottom width. This stave shape causes the load resulting fromthe weight of the brickwork or other material forming the inwall 104 ofthe shaft to be carried down into the reentrant corner between the shaftshell portion 91 and the inwardly extending portion of mantle 93; thisoccurs because the material forming the inwall bears on the inwardlyprojecting wider upper portions of these lowermost staves to urge thesestaves downwardly into such corner to distribute the load through thelining material located outwardly of these staves, to the mantle andadjacent portion of the shell.

The design of FIG. 10 permits independent assembly of the supportingstructure 2 and connector members 94, independent assembly of the shell89, and subsequent joining of the connector members 94 to the shell bystrips 96. In this embodiment, moreover, the ring members 98 and 99 atthe tops and bottoms of beams 38 of the frame 12 resist tilting of thebeams from the weight of the furnace or thermal expansion or contractionof the furnace shell on heating or cooling of the furnace. The remainderof the furnace structure illustrated by FIG. 10 may be like that of FIG.9.

In the modification of FIG. 11 shown as applied to the furnace of FIG.9, the furnace 81 comprising shell 107 is supported from a supportingstructure 2 identical with that of FIGS. 14, comprising a frame 12 thatis supported by legs, not shown, like the widely spaced legs 14 of theprevious embodiment. As in the previous embodiment, four deep I-girders38 are joined at their ends to define a frame 12 that is square in plan.At points of equal deflection on the frame 12 and equiangularly spacedaround the furnace shell there are radially extending deep, stiff,generally vertical connector members 108 formed of steel plate that arefixed to the webs 39 of the beams 38 of frame 12, as by welding orbolting, and that are rigidly connected to the furnace shell above themantle by connector strips 109 bolted to members 108 and to radiallyextending lugs 111 fixed to the shell.

In the supporting structure, there is a ring member 112 which preferablyis identical to member 51 of FIGS. 14, inclusive, and to member 98 ofFIG. 9 in that it is of equal-sided equiangular octagonal shape in plan,fixed to the tops of upper flanges 40 of the beams of the frame 12.Another preferably identical ring member 113 is similarly fixed to andlocated on the undersides of the bottom flanges 41 of the beams 38.

In this embodiment, conventional generally horizontally extendingcooling plates 114 are provided, through which cooling water iscirculated in the usual manner.

The ring members 112 and 113 stabilize the frame 2 and the furnace shellin the same manner as do corresponding members in the structure of FIG.6 by preventing harmful tilting of beams 38 of frame 12. Preferably,adjustable struts are provided, of the type and location of struts 53and 56 of the embodiment of FIGS. lS, to perform the same functions. Theremainder of the apparatus, not shown, may be identical with theapparatus of FIG. 9.

The furnace structures illustrates in each of FIGS. 9, l0 and 11 providemany of the advantages indicated above in connection with the furnacestructure of FIGS. l8 as arising from improved accessibility to thelower portion of the furnace because of the widely spaced legs, althoughit does not provide the advantages arising from the suspended hearth,such as rapid replacement of the suspended hearth as a whole, unimpededdownward expansion, and increased cooling area. However, in thestructures of FIGS. 9 to 11, the supporting structure 2 formed of theframe 12 and the legs 14 can be designed to be stiff enough to supportthe load of the furnace above the connector members connecting the frame12 to the furnace shell, but limber enough so that if the portion of thefurnace below the connectors contracts on cooling, the supportingstructure can permit sufficient downward movement of the upper portionof the furnace to permit the lower and upper portions of the furnacewall in the vicinity of the mantle to remain an essentially continuouswall, and thus eliminate the necessity for an expansion joint that isoften located near the mantle in conventional furnaces, which expansionjoint is often a source of trouble.

In the embodiment of FIGS. 1 to 8, the entire weight of the furnace andstructure supported by the furnace is supported by structure 2. This,therefore, completely avoids the previously discussed problems arisingin conventional American and European furnaces because the portions ofthe furnace above the bosh must be supported by the hearth and boshportions, since in this embodiment the hearth and bosh are notsupporting elements.

In each of the embodiments of FIGS. 9 to 11, inclusive supportingstructure 2 is so designed that at least about 25 percent and preferably50 percent or even more, of the weight of the furnace above theconnections of the furnace above the bosh to frame 12 is at all timescarried by the supporting structure 2, even when the furnace is hot andthe hearth and bosh portions lengthen to positions where otherwise theywould support the portion of the furnace above the bosh. Therefore,

the hearth and bosh portions need not be designed to carry as muchweight as in conventional American or European blast furnaces, and thissubstantially minimizes and can eliminate most if not all of theproblems described above as arising in conventional furnaces because thehearth and bosh portions must support essentially all of the weight ofthe furnace and apparatus above the bosh.

Preferably, in each of the previously described embodiments, the legs 14of the supporting structure 2 are hollow and are filled with pouredconcrete introduced by conventional apparatus and methods throughopenings 120 (FIGS. 3, 4 and in the upper ends of the legs 14.Preferably the concrete 121 extends essentially from the bottom of eachleg as shown in FIG. 7 to the upper/end of each leg as shown in FIGS. 4and 10, to insure that when hardened the concrete extends throughout atleast the portion of each leg that is subject to deflection. If desired,as shown in FIGS. 7 and 8, reinforcing steel 122 may be embedded in theconcrete 12]. Preferably the concrete is of the type that does notshrink, or that may even expand slightly, on curing to insure permanentfirm contact of the concrete with the inner walls of the legs.

Maximum benefits are provided when the hollow legs 14, while empty ofconcrete, are, prior to loading of supporting structure 2, firstprestressed by having their lower ends moved outwardly from theirinitial unstressed position in a direction and by an amount essentiallycorresponding to the direction and amount that the lower end of each legwould move outwardly from its unstressed position if the supportingstructure 2 of which the leg forms a part was subjected to a loadcorresponding to the furnace, so that the legs are deflected asindicated by the full lines in FIG. 6, the lower ends of the legs beingthen locked in such positions; structure 2 is then loaded with thefurnace so the legs 14 assume positions in which they are essentiallyundeflected as shown in broken lines in FIG. 6 and in full lines inFIGS. 1, 2 and 9 in which the legs are shown straight; and the legs arethereafter filled with poured concrete which is then allowed tosolidify.

The concrete, after it has hardened and cured, stiffens the legs 14 andacts to maintain them in their undeflected conditions, in which theyhave their maximum strength. This is particularly important since theframe structure as initially designed has deep, stiff cross beams 38 andlegs 14 which, while strong enough to support the load of the furnaceeven before the addition of the concrete, are relatively limber sincethey are made of steel and capable of being deflected in theprestressing operation. Addition and curing of the concrete while thelegs are in their straight or undeflected positions increases thestiffness of the legs and their resistance toward bending.

The concrete in the legs also adds substantial mass to the legs whichare of relatively large cross section and considerable length; forexample, if the legs are circular in cross section they may be as muchas 5 feet or even more in diameter for a furnace of modern largecapacity. This large added mass and the resistance of the concrete tocompressive forces provides added protection against damage from impactson the legs, such as might occur from a derailed railroad car, thusadding to the safety of the furnace structure. The added mass of theconcrete also acts to substantially absorb and dissipate the energy ofeither steady or transient vibrations to which the legs 14 or thefurnace structure as a whole may be subjected, thus damping outvibrations which couldotherwise be harmful. Steady vibrations couldoccur from operation of sifting machinery or unbalanced equipment whichcould cause undesirable resonance; transient vibrations could occur fromseismic shocks or passing railroad rolling stock. The damping action ofthe large mass of concrete in each leg prevents undesirable resonance orharm from such vibrations.

The concrete in each leg can also act as a high capacity heat sink thatcan absorb and transmit away from a point of localized exposure on theleg heat from hot metal, slag or coke that might approach or contact thelegs in the event of a furnace breakout. The concrete thus providesadded protection for the legs in this respect.

The above advantages of the concrete filling are provided if the legsare of circular cross section as shown, or of other hollow crosssections including polygonal cross sections such as a square crosssection.

It is apparent that various modifications can be made in any of thefurnace structures illustrated. For example, the furnace tops in FIGS.1, 2 and 9 could be supported from the auxiliary supporting structure23, instead of from the top of the furnace shaft, although when the topis supported on the furnace as in the illustrated embodiments advantagesarise because the top can move upwardly and downwardly as the furnaceshaft expands and contracts. The connector means of FIGS. 10 and 11could be used in the structure of FIGS. l8, as well as in the structureof FIG. 9.

While four legs of circular cross section are shown, one each corner ofa four-sided supporting frame, supporting frames of different shapes,preferably polygonal, supported by a different number oflegs may beused, and the legs may be of circular or other, even polygonal, crosssection. In any event the number and cross section of the legs should besuch that adequate support and stability are provided. It appears thatfor most, if not all, uses four legs and a square-sided supporting frameare most advantageous from the standpoint of stability, adequatesupport, economy and cost. The legs in the illustrated embodiment arediagonally inclined, for increased stability of the furnace structure;however, they may be vertically disposed, if desired.

Other modifications will be apparent to those skilled in the art. It isintended that the patent shall cover, by suitable expression in theappended claims, whatever features of patentable novelty reside in theinvention.

We claim:

I. Shaft furnace apparatus comprising an upright shell, a permanentsolid inwall lining in said shell, and hollow upright and transverselyextending cooling staves embedded in said lining, the cross-sectionalwidth of said staves being substantially less than the cross-sectionaldepth of said staves and said staves having lower portions that projectdownwardly for a substantial portion of the depth of the staves, theupper portions of said staves being substantially wider than the lowerportions of said staves and projecting into said lining to providesupport for said lining.

2. The apparatus of claim 1 in which said staves are arranged so thatcertain of them are located above and in close proximity to lowerstaves, the upper portions of said lower staves being substantiallywider than the lower portions of the staves above them, so that theupper portions of said lower staves provide support for said lining.

3. The apparatus of claim 2 in which said upper portions of said lowerstaves are about twice the width of the lower portions of said upperstaves.

4. The apparatus of claim 2 in which said shell is a shaft portion shellof a blast furnace, in which there is a mantle at the lower end of saidshaft portion shell extending inwardly of said shell and forming withsaid shell a reentrant corner, and in which said staves are located inthe lining in said reentrant corner to provide cooling and support forthe lining.

5. The apparatus of claim I in which the upper portions of said stavesare about twice the width of the lower portions of said staves.

said shell and forming with said shell 2. reentrant corner, andin whichsaid staves are located in the lining in said reentrant comer to providecooling and support for the lining.

1. Shaft furnace apparatus comprising an upright shell, a permanentsolid inwall lining in said shell, and hollow upright and transverselyextending cooling staves embedded in said lining, the cross-sectionalwidth of said staves being substantially less than the cross-sectionaldepth of said staves and said staves having lower portions that projectdownwardly for a substantial portion of the depth of the staves, theupper portions of said staves being substantially wider than the lowerportions of said staves and projecting into said lining to providesupport for said lining.
 2. The apparatus of claim 1 in which saidstaves are arranged so that certain of them are located above and inclose proximity to lower staves, the upper portions of said lower stavesbeing substantially wider than the lower portions of the staves abovethem, so that the upper portions of said lower staves provide supportfor said lining.
 3. The apparatus of claim 2 in which said upperportions of said lower staves are about twice the width of the lowerportions of said upper staves.
 4. The apparatus of claim 2 in which saidshell is a shaft portion shell of a Blast furnace, in which there is amantle at the lower end of said shaft portion shell extending inwardlyof said shell and forming with said shell a reentrant corner, and inwhich said staves are located in the lining in said reentrant corner toprovide cooling and support for the lining.
 5. The apparatus of claim 1in which the upper portions of said staves are about twice the width ofthe lower portions of said staves.
 6. The apparatus of claim 1 in whichsaid shell is a shaft portion shell of a blast furnace, in which thereis a mantle at the lower end of said shaft portions shell extendinginwardly of said shell and forming with said shell a reentrant corner,and in which said staves are located in the lining in said reentrantcorner to provide cooling and support for the lining.